Metal alloy



Patented Jan. 23, 1940 UNITED STATES METAL ALLOY Vincent T. Malcolm,Indian Orchard, Mass., as-

signor to The Chapman Valve Manufacturing Company, Indian Orchard,Mass., a corporation of Massachusetts Application November 30, 1938,

No Drawing.

Serial No. 243,199

1 Claim. (Cl. 75-126) This invention relates to an alloy steel which isadapted among other purposes for the manufacture of valves, tubes, pipelines, and equipment adapted for use in oil refineries and the like.

The principal objects of the invention are directed to the provision ofan alloy steel which is not adversely affected when made into parts suchas valves, pipe lines and other equipment that is subjected to elevatedtemperatures. and pressures and to the action of various gases and acidswhich ordinarily very unfavorably afiect ordinary steels.

The steel of this invention is characterized by an improved creep ratio,resistance to corrosion, fine grain, and improved impact properties. Asspecial features, by reason of its composition, hydrogen-embrittlementand decarburization is practically eliminated.

According to present day practices in oil refineries, metal parts suchas valves, pipe lines and equipment are frequently subjected to theaction of various acids and gases such as hydrogen, propane, butane,ethane,-methane, naphthionic and suiphonic acids, etc. The novelcombination of elements constituting the alloy steel of this inventionrenders parts made therefrom peculiarly capable'oi withstanding theactions of these substances, at least to the extent that it'is noteasily, it at all, afiected adversely thereby.

Ordinary steels when so subjected within the range of from 700 to 1000F. have an inherent tendency towards decarburization and hydrogenparedwith the creep-rate of the steel disclosed in United States LettersPatent #1,915,065 issued to V. T. Malcolm on June 20, 1933. The steel ofthis invention, as to its ability to resist corrosion, is no less butslightly greater than that obtaining in connection with the prior artsteel.

According to this invention, the steel alloy includes chromium andeither tungsten or molybdenum, with vanadium as an important element.These are combined with sulphur, phosphorus, and silicon and it isbelieved that the tungstenvanadium or molybdenum-vanadium elements areresponsible in a large part for the ability of the steel of thisinvention to resist the various gases and acids above-mentioned whichare encountered in present day oil refinery processes and its ability toovercome hydrogen-embrittlement and decarburiration.

As stated, the steel also has a lower creep rate as well as fine grainand improved impact properties.Thecompositionotthealloysteeloitbllinvention, more particularly thechromium, the tungsten or molybdenum, and the vanadium elements, may bevaried within wide limits, but a composition within the range set forthin the following analysis will produce an alloy steel having,

the above characteristics and adapted to overcome the objectionsinherent in prior art steeel:

, Per cent Carbon Trace up to .50 Chromium 4.00 to 8.00 Tungsten .75 to2.00

0r molybdenum .5 to 1.0 Sulphur, maximum .05 Phosphorus, maximum .05Silicon .3 to 2.0 Vanadium .5 to 2.0 Iron Substantial balance A morespecific analysis of the steel of this invention is as follows: a

From the above it will be noted'that either tungsten or molybdenumchromium with the addition of vanadium form the important elements toprovide the alloy of this invention and having the desiredcharacteristics and properties.

While I have described the invention in great detail and with respectto' the present preferred form thereof, it is not desired to be limitedthereto since many changes and modifications may be made therein withoutdeparting from the spirit and scope oi the invention.

What it is desired to claim and secure by Letters Patent of the UnitedStates is:

A new low-creep alloy steel containing chromium and carbon and siliconand which is resistant to the action of such corrosive elements asmethane, propane, naphthionic acid, and sulphonic acid at high temeratures in the neighborhood o! 1200 F. comprising in combination, about6% chromium, a maximum of .2% carbon, at least 1% and a maximum of 2%silicon, relatively small amounts of both sulphur and phosphorus, themaximum of each being .05%, more than .5% but not more than 2% ofvanadium, at

least .5% and a maximum of 2% of one of a group including tungsten andmolybdenum, and the balance substantially all iron.

VINCENT 'r. mucous/r.

